The invention relates to a roller with a roller surface which is to be heated or cooled by means of a fluid, having a heat exchange apparatus comprising at least one chamber for the fluid which is adjacent to the roller surface and is open relative to said roller surface, the surfaces of the chamber walls which face the roller surface forming a gap with the roller surface, and having a fluid supply for the chamber and having clamping means for clamping the chamber in the circumferential direction of the roller.
A roller of this kind is known from U.S. Pat. No. 4,149,397, for example. According to this specification, the roller surfaces of the working rollers are thermally affected by means of external hydrostatic support means. The pressure medium of the hydrostatic support means, which is used as the coolant in this specification, is fed via choke bores to hydrostatic, chamber-like bearing pockets which are open relative to the roller surface which is to be cooled, and it flows out of said bearing pockets through the gap between the end faces of the chamber walls and the roller surface, forming a substantially constant hydrostatic film of coolant, and there is a particularly good heat transfer in the gap chamber, compared with the amount of coolant required.
This known arrangement is highly sensitive to the slightest pressure fluctuations in the pressure medium or coolant fed in. Thus, for example, any soiling or even blockage of the choke inlets will have enormous influence on the cooling effect. Moreover, the temperature variation in the pressure medium supplied, en route from the pressure medium source to the place or heat release at the roller surface, is so great that it is almost impossible to calculate in advance the desired final temperature of the pressure medium which releases its heat at the roller surface.
Other known arrangements in which coolants or heating media are sprayed on to the roller surface or the inner wall of a roller shell are known from CH-PS No. 577,598, FIG. 4 or U.S. Pat. No. 885,283, for example. The method of influencing the heat of rollers known from these specifications is widely used and is totally unaffected by pressure fluctuations in the pressure medium or heat exchange medium supplied. However, in all constructions of this type, large quantities of pressure medium have to be fed in, requiring pumping capacities which are disproportinately large in relation to the efficiency obtained, particularly when the heat exchange medium is at fairly high temperatures. Moreover, the elimination or recycling of the heat exchange medium causes problems when such large amounts are involved.